Pile is widely used as deep foundation in civil engineering. The dynamic interaction between pile and soil is an important problem in the field of soil-structure interaction. This paper established a model to calculate the seismic response of pile-soil couple system. In this model, pile and soil are regarded as lumped mass, soil was divided into two parts: the far region soil and near pile region soil. These two parts are simulated by different mechanical characters. A differential equation of motion of pile-soil couple system was established in the paper, this differential equation can be solved by Wilson-θ method. An example was introduced to study the behavior of pile-soil couple system.